Optimization of heterotrophic cultivation of Chlorella sp. for oil production.

The oleaginous microalga Chlorella sp. LAM-H screened from freshwater was proven to be a prospective feedstock for oil production according to its fatty acid composition. In order to enhance lipid production, response surface methodology (RSM) was used with central composite design (CCD) to optimize the heterotrophic cultivation of microalgae. The experiment results showed that a satisfactory second-order polynomial regression equation was achieved with a high coefficient of determination (R(2)=0.9911) in analysis of variance. The effects of individual factors and their interactions on lipid productivity were successfully revealed. The greatest lipid productivity reached 247.16 mg l(-1) d(-1) under the optimal conditions of glucose concentration 26.2 g l(-1), sodium nitrate concentration 2.06 g l(-1) and temperature 28.18 °C. Moreover, validation tests were performed and the results were very close to the predicted values. It was demonstrated that the obtained model was effective for predicting lipid productivity of the isolated microalga.